JPH03136572A - Reader - Google Patents

Abstract

PURPOSE:To reduce the manufacture cost and to make the size of the reader small without need of a ROM having been employed for a conventional reader by correcting an electric signal corresponding to the lightness with a simple arithmetic circuit. CONSTITUTION:A data Vin is given to a B1 input of a multiplier circuit 11 and an A2 input of an adder circuit 12. A constant (a) from a register 16 is given to an A1 input of the multiplier circuit 11, the A1 input and the B1 input are subject to multiplication processing and the result of product is given to an A4 input of a subtraction circuit 14. A constant (b) from a register 17 is given to a B2 input of the adder circuit 12, the A2 input and the B2 input are subject to addition processing and the result of sum is given to a B3 input of a division circuit 13. A constant (c) from a register 18 is given to an A3 input of the division circuit 13, the A3 input and the B3 input are subject to division processing and the result of division is given to a B4 input of the subtraction circuit 14. The subtraction circuit 14 applies subtraction processing to the A4 input and the B4 input and the result of subtraction is given to an A5 input of an adder circuit 15. A constant (d) from a register 19 is given to a B5 input of the adder circuit 15, the A5 input and the B5 input are subject to addition processing and the output from the adder circuit 15 is a data Vout after gradation correction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a reading device suitably implemented in an image processing device such as a facsimile machine.

Although there is an approximately proportional relationship between the output value of the light-receiving element used in conventional image processing devices and the brightness, there is a logarithmic relationship between the human confusion about brightness and the brightness. A relationship is established. Therefore, if an image is created using the output value of the light-receiving element as it is, there will be a deviation from the image seen by a human, and it is necessary to correct the output value (gradation data).

FIG. 3 is a block diagram showing the basic configuration of a conventional gradation correction circuit. An output value from a reading means 1 implemented by a CCD (charge-coupled device) or the like is applied to an A/D (analog/digital) converter 2 and converted into, for example, 8-bit digital data.

This digital data is stored in the ROM (
read-only memory) 3. In ROM3,
The gradation correction data is stored in address "0" to address r255J, and by giving the data from the A/D converter 2 to the ROM 3 as address data, the gradation corrected data is output. become.

Problems to be Solved by the Invention The gradation correction circuit as described above requires ROM3, so if it is difficult to incorporate a circuit with the same function as a ROM internally, such as in a gate array, an external The problem is that the ROM 3 is attached to the ROM 3, and a terminal for transmitting and receiving data to and from the ROM 3 is required, which increases the manufacturing cost.

An object of the present invention is to provide a reading device that can reduce manufacturing costs and simplify the circuit configuration.

Means for Solving the Problems The present invention comprises a plurality of light receiving elements arranged and reading means for deriving an electrical signal corresponding to brightness for each light receiving element, and calculating the output from the reading means. The reading device is characterized in that it includes an arithmetic circuit that corrects the electric signal to an electric signal corresponding to a predetermined brightness.

Function According to the present invention, the reading means is constructed by arranging a plurality of light receiving elements, and derives an electric signal corresponding to brightness for each light receiving element. This electrical signal is given to an arithmetic circuit.

The arithmetic circuit corrects the electrical signal from the reading means into an electrical signal corresponding to a predetermined brightness.

Therefore, there is no need to use a ROM to correct the electrical signal from the reading means as in the conventional case, and the correction can be performed using a simple arithmetic circuit.

This reduces the manufacturing cost of the reading device and
It also becomes possible to downsize the reading device.

Embodiment FIG. 1 is a block diagram showing the basic configuration of a reading device which is an embodiment of the present invention. The output from the reading means 7, which is composed of a plurality of light receiving elements 6 arranged in an array, is converted into digital data by an A/D converter 8, and further subjected to shading correction by a shading correction circuit 9. Shading correction refers to the fact that due to the optical characteristics of the optical system such as the lens that constitutes the reading means 7 and the optical characteristics of the light-receiving element, the peripheral parts of the read image are darker than the brightness of the central part. , is a correction performed to flatten the brightness of the entire image.

The data Vin after shading correction is processed by the arithmetic circuit 10.
is corrected to data Vout by.

The arithmetic circuit 10 calculates data Vout according to the first equation below.
Calculate.

The first equation above can be used as an approximate equation for a logarithmic number used for gradation correction.

FIG. 2 is a graph showing changes in the output value of the light receiving element 6 with respect to brightness and changes in how humans perceive brightness. A nearly proportional relationship holds true between the light receiving element 6 and brightness, but a logarithmic relationship holds true between the human perception and brightness.

Therefore, a deviation occurs between the image created based on the output value of an original read by the light-receiving element 6 and the image when a person views the original.In order to correct this deviation, the above-mentioned Formula 1 data Vin is given to the B1 human power of the multiplier circuit 11 and the A2 human power of the adder circuit 12. The constant a from the register 16 is given to the A1 human power of the 1 multiplier circuit 11; A multiplication process is performed between B1 and human power, and the calculation result is sent to A of the subtraction circuit 14.
Given to 4 people. The B2 input of the adder circuit 12 is given a constant value from the register 17, and the adder circuit 12
Addition processing is performed between the 2-manpower and the B2-manpower, and the calculation result is given to the 83-manpower of the division circuit 13.

Constant C from register 18 is input to A3 of divider circuit 13.
is given, the division circuit 16 performs a division process between A3 manpower and 83 manpower, and the calculation result is given to 84 manpower of the subtraction circuit 14. The subtraction circuit 14 performs subtraction processing between the A4 manpower and the 84 manpower, and the calculation result is given to the A5 manpower of the addition circuit 15.

The constant d from the register 19 is added to the 85 input of the adder circuit 15.
is given, the adder circuit 15 performs addition processing between A5 human power and B5 human power, and the output value from this adder circuit 15 is t.
After the Li tone correction, the value becomes -ta Vout.

Also, the constant a output by registers 16.17 and 18.19
, b, c, and d can be changed using a CPU (central processing unit W) or the like, thereby making it possible to perform accurate gradation correction according to the optical characteristics of the light-receiving element 6. Also, if necessary, the constants a, b, c, d can be changed to r□,
By doing so, the arithmetic circuit 10 can be further simplified.

As described above, according to this embodiment, since the gradation data is corrected by a simple arithmetic circuit, there is no need to use a ROM as in the past, and manufacturing costs can be reduced. Furthermore, it becomes possible to incorporate the arithmetic circuit into a gate array or the like of the reading device, and the size of the reading device can also be reduced.

Effects of the Invention As described above, according to the present invention, a simple arithmetic circuit is used to correct the electrical signal corresponding to the brightness, so there is no need to use a ROM as in the past, and manufacturing costs are reduced. At the same time, it is also possible to downsize the reading device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of a reading device which is an embodiment of the present invention, and FIG. 2 shows a light receiving element 6 for brightness.
FIG. 3 is a block diagram showing the configuration of a conventional gradation correction circuit. 6... Light receiving element, 7... Reading means, 10... Arithmetic circuit, 11... Multiplication circuit, 12.15... Addition circuit, 13... Division circuit, 14... Subtraction circuit , 16.1
7,18゜19...Register

Claims (1)

[Scope of Claims] Reading means configured by arranging a plurality of light receiving elements and deriving an electrical signal corresponding to the brightness for each light receiving element, and a predetermined brightness by calculating the output from the reading means. A reading device comprising: an arithmetic circuit that corrects an electric signal corresponding to the electric signal.